I have never used them and dont think i will but i understand you are only thinking of Lachies well being. I think the girls are just telling you this so you dont waste any money, they are just trying to help!
By doing what your doing now , reading singing etc will give Lachie a better start than plonking him in front of the tv! Social interaction is far better than tv! Your doing a great job just being with him!
I really beleive these type of things were created to make money off parents, as we all want our child to succeed!

I know you are probably asking as you want give Lachie the best start, but in all honesty you really dont need them! Maybe someone who has used them will pop in and tell you there experience! x